A student designs an experiment where he takes a small wood car with 1.0 inch diameter wheels and rolls it down a ramp. The student measures the speed of the car when it reaches the bottom of the ramp. The student then takes a small plastic car with 1.5 inch diameter wheels and repeats the process. Finally, the student takes a small metal car with 2.0 inch diameter wheels and repeats the process a final time. The student notes that the metal car had the fastest speed at the bottom of the ramp.

The student can conclude:

metal cars increase speed faster than plastic or wood cars
cars with large diameter wheels increase speed faster than cars with small diameter wheels
both of the above
none of the above